Radioimmunoassay of elastin.

Highly purified elastin was prepared from bovine ligamentum nuchae by hot alkali extraction. Antisera to the protein, developed against suspensions or acid solubilized preparations, were obtained from rabbits and guinea pigs. Of a large number of proteins, only insoluble elastin (from the aortae of several animal species) and tropoelastin, the putative soluble precursor, reacted with the antisera as determined by double antibody radioimmunoassay. Nanogram quantities of insoluble elastin can be detected following solubilization of the protein by brief acid treatment. Tropoelastin can be determined in the microgram range. The radioimmunoassay should permit determination in tissues, in fluids, and in in vitro cultures of soluble, newly synthesized elastin, mature insoluble elastin, and intermediate forms of the fibrous protein which may have heretofore escaped detection. A sensitive assay for elastin should also permit the acquisition of information concerned with connective tissue turnover during development, aging, and disease.